linux-kernel - [PATCH] NTB: Fix UB/bug in ntb_mw_get

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Message-Id: <20171130213941.21114-1-fancer.lancer@gmail.com>
Date:   Fri,  1 Dec 2017 00:39:41 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     jdmason@...zu.us, dave.jiang@...el.com, Allen.Hubbe@....com,
        Shyam-sundar.S-k@....com, Xiangliang.Yu@....com
Cc:     Sergey.Semin@...latforms.ru, linux-ntb@...glegroups.com,
        linux-kernel@...r.kernel.org, Serge Semin <fancer.lancer@...il.com>
Subject: [PATCH] NTB: Fix UB/bug in ntb_mw_get_align()

Simple (1 << pidx) operation causes undefined behaviour when
pidx >= 32. It must be casted to u64 to match the actual return
value of ntb_link_is_up() method, so to have all the possible
peer indexes covered and to get rid of undefined behaviour.
Additionally there are special macros in "linux/bitops.h" to perform
the bit-set-shift operations, so it's recommended to have them used
for proper bit setting.

Signed-off-by: Serge Semin <fancer.lancer@...il.com>
---
 include/linux/ntb.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/ntb.h b/include/linux/ntb.h
index c1646f2c6344..488e586fb76c 100644
--- a/include/linux/ntb.h
+++ b/include/linux/ntb.h
@@ -764,7 +764,7 @@ static inline int ntb_mw_get_align(struct ntb_dev *ntb, int pidx, int widx,
 				   resource_size_t *size_align,
 				   resource_size_t *size_max)
 {
-	if (!(ntb_link_is_up(ntb, NULL, NULL) & (1 << pidx)))
+	if (!(ntb_link_is_up(ntb, NULL, NULL) & BIT_ULL(pidx)))
 		return -ENOTCONN;
 
 	return ntb->ops->mw_get_align(ntb, pidx, widx, addr_align, size_align,
-- 
2.12.0